One of the reasons for frequent use of small wall clocks for bathroom is its portability. It is not mandatory that you have to mount the clock onto the wall or anywhere else. There are other options as well. A small clock can be readily placed anywhere, like you can place the clock onto the shelf as well. The smaller size of the clocks makes them portable and for the same reason most of the people would prefer to purchase small wall clocks for bathroom. Portable clocks can be placed at the different locations whenever required.